Periodontitis vaccine and related compositions and methods of use

ABSTRACT

An immunogenic composition, a periodontal vaccine formulation containing the immunogenic composition, and methods for treating or preventing periodontal disease are provided, where the methods involves administering an immunologically effective amount of the composition or vaccine formulation to a subject. The immunogenic composition contains at least one polypeptide that comprises: an Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a Porphyromonas bacterium; and an HA1 antigen sequence, an HA2 antigen sequence, or both an HA1 antigen sequence and an HA2 antigen sequence, wherein the HA1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 1 contained within an RgpA Gingipain protein of a Porphyromonas bacterium, and the HA2 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 2 contained within an RgpA Gingipain protein of a Porphyromonas bacterium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 17/035,242, filed Sep. 28, 2020, which is a continuation of U.S. patent application Ser. No. 16/158,155, filed Oct. 11, 2018, now U.S. Pat. No. 10,835,590, which issued Nov. 17, 2020, which claims priority under 35 U.S.C. § 119(e)(1) to provisional U.S. Patent Application Ser. No. 62/571,582, filed Oct. 12, 2017, the contents of each of which are incorporated herein by reference in its entirety.

SEQUENCE LISTING

The contents of the file named STRO_002_03US_SeqList_ST25.txt, which was created on May 4, 2021, and is 17.7 KB in size are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates generally to the prevention and treatment of periodontitis, and more particularly relates to a periodontal vaccine composition and a method for its use.

BACKGROUND

Periodontal diseases, collectively referred to as “periodontitis,” are commonly occurring, yet complex chronic oral inflammatory diseases that destroy the soft and hard tissues supporting the teeth. If left untreated, the loss of the alveolar bone around the teeth can result in the loosening and subsequent loss of teeth. Periodontal disease is among the most common human diseases of bacterial origin, with recent studies indicating that approximately 60% of individuals over 40 years of age in the United States have moderate or severe periodontitis and possess measurable oral bone loss. The prevalence of periodontitis increases with age; see Eke et al. (2012) J Dent. Res. 91(10): 914-920. Severe generalized periodontal disease occurs in an estimated 5-20% of individuals globally (Burt et al. (2005) J. Periodontol. 76(8): 1406-19, often resulting in multiple tooth loss by middle age, and the economic burden of this disease is significant, with 2010 data estimating the economic impact at $54 billion in the US alone (Listl et al. (2015) J. Dent. Res. 94(10): 1355-61.

Periodontitis is characterized according to both severity and cause in a classification system with seven recognized major categories: (1) gingival disease, or “gingivitis,” involving inflammation of the gingiva; (2) chronic periodontitis, a slowly progressive disease that may be either localized or generalized; (3) early onset, or “aggressive” periodontitis; (4) periodontitis associated with a systemic disease such as diabetes mellitus, AIDS, and leukemia; (5) necrotizing periodontal disease; (6) periodontal abscesses; and (7) periodontitis associated with endodontic lesions. The latter six categories are designated “destructive” periodontal diseases because the damage caused is irreversible. See Armitage (1999) Ann. Periodontol. 4(1): 1-6. The symptoms of periodontitis include inflamed or bleeding gums, gingival recession, pockets between the teeth and gums, and, in the case of severe periodontitis, loosening or loss of teeth. Treatments will depend on the extent and cause of the disease, and include scaling, root planing, antibiotic therapy, and surgery. Scaling and root planing often have to be carried out multiple times, antibiotic therapy can be problematic insofar as beneficial oral microbes can be killed along with the pathogenic bacteria, and oral surgery is a generally undesirable solution of last resort.

Periodontitis is initiated by the presence of keystone bacteria such as Porphyromonas gingivalis. Porphyromonas organisms possess an array of molecules contributing to its overall virulence, including fimbriae and gingipains (a group of cysteine proteases) that impact various aspects of disease pathogenesis including attachment of bacteria to cells and other community microbes, development of inflammation, and microbial dysbiosis associated with periodontal disease; see Lamont et al. (1998) Microbiol. Mol. Biol. Rev. 62(4): 1244-63, and Bostanci et al. (2012) FEMS Microbiol. Lett. 333(1): 1-9. Several of these bacterial virulence factors have been explored as potential targets for vaccine development. See, e.g., Lamont et al., supra; Arjunan et al. (2016) Mol. Oral Microbiol. 31(1): 78093; Takahashi et al. (2006) Cell Microbiol. 8(5):738-57; Malek et al. (1994) J. Bacteriol. 176(4): 1-52-9); Gibson et al. (2001) Infect. Immun. 69(12): 7959-63; and Evans et al. (1992) Infect. Immun. 60(7): 2926-35.

A vaccine to treat periodontitis—and possibly prevent periodontitis as well—would eliminate the need for repeated clinical interventions and/or oral surgery. Development of an effective therapeutic and/or prophylactic vaccine for periodontal disease would be especially useful as the disease occurs in a significant portion of the adult population. However, periodontitis is a multifactorial disease with factors including bacterial composition of dental plaque, host genetic make-up, and environmental factors contributing unique barriers to a basic understanding of periodontal disease pathogenesis and the potential for targeted vaccine development.

An ideal periodontitis vaccine would achieve therapeutic efficacy in subjects with periodontitis and be effective in the prophylactic context as well. The need for aggressive clinical interventions would be eliminated, and the number of individuals suffering from periodontal diseases would substantially decrease. In addition, an ideal vaccine would be straightforward to manufacture using a cost-effective process amenable to large-scale production.

SUMMARY OF THE INVENTION

The invention is addressed to the aforementioned need in the art and provides an immunogenic composition, a vaccine formulation comprising the composition, and methods for treating and preventing periodontal disease.

In a first embodiment of the invention, an immunogenic composition is provided comprising at least one polypeptide that comprises: (a) an Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a Porphyromonas bacterium; and (b) an HA1 antigen sequence, an HA2 antigen sequence, or both an HA1 antigen sequence and an HA2 antigen sequence, wherein (i) the HA1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 1 (also referred to herein as “Gingipain HA1” or “HA1”) contained within an RgpA Gingipain protein of a Porphyromonas bacterium, and (ii) the HA2 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 2 (also referred to herein as “Gingipain HA1” or “HA1”) contained within an RgpA Gingipain protein of a Porphyromonas bacterium.

In one aspect of this embodiment, the at least one polypeptide comprises a first polypeptide that comprises: (a) an Mfa1 antigen sequence and an HA1 antigen sequence; (b) an Mfa1 antigen sequence and an HA2 antigen sequence; or (c) an Mfa1 antigen sequence, an HA1 antigen sequence, and an HA2 antigen sequence. It will thus be appreciated that the first polypeptide may be a fusion protein that includes the Mfa1 antigen sequence as well as the HA1 antigen sequence and/or the HA2 antigen sequence. In a related aspect, the at least one polypeptide comprises (a) a first polypeptide comprising an Mfa1 antigen sequence; and (b) a second polypeptide comprising an HA1 antigen sequence, an HA2 antigen sequence, or both an HA1 antigen sequence and an HA2 antigen sequence. Thus, in this aspect the Mfa1 antigen sequence is within one polypeptide, and the HA1 and HA2 antigen sequences are within a second polypeptide, which is a fusion polypeptide if both are present.

In another aspect of this embodiment, the at least one polypeptide of the immunogenic composition comprises a first polypeptide comprising an Mfa1 antigen sequence, a second polypeptide comprising an HA1 antigen sequence, and a third polypeptide comprising an HA2 antigen sequence. Thus, in this aspect, there are three distinct polypeptides each containing one of the Mfa1, HA1 and HA2 antigen sequences.

In a related aspect, the Mfa1 antigen sequence, the HA1 antigen sequence, and the HA2 antigen sequence are substantially homologous to an immunogenic amino acid sequence of the Mfa1 fimbrilin polypeptide, Gingipain HA1, and Gingipain HA2, respectively, of a Porphyromonas species selected from P. gingivalis, P. gulae, P. cangingivalis, P. gingivicanis, P. canoris, P. salivosa, and P. circumdentaria.

In another aspect of this embodiment, the Mfa1 antigen sequence, the HA1 antigen sequence, and the HA2 antigen sequence are substantially homologous to an immunogenic amino acid sequence of the Mfa1 fimbrilin polypeptide, Gingipain HA1, and Gingipain HA2, respectively, of P. gingivalis.

In another aspect of this embodiment, the Mfa1 antigen sequence, the HA1 antigen sequence, and the HA2 antigen sequence are substantially homologous to an immunogenic amino acid sequence of the Mfa1 fimbrilin polypeptide, Gingipain HA1, and Gingipain HA2, respectively, of P. gulae.

In another embodiment of the invention, a periodontitis vaccine formulation is provided that comprises an immunogenic composition as described above and a pharmaceutically acceptable excipient. In the usual instance, the formulation contains at least one excipient, where the at least one excipient is selected from vehicles, solubilizers, emulsifiers, stabilizers, preservatives, isotonicity agents, buffer systems, dispersants, diluents, viscosity modifiers, and absorption enhancers. The vaccine may, in addition or in the alternative, include at least one adjuvant.

In one aspect of this embodiment, the vaccine formulation is formulated as sterile injectable solution. In a related aspect of this embodiment, the vaccine formulation is formulated as a lyophilized composition to be rehydrated prior to use.

In another embodiment, a method is provided for immunizing a subject against periodontal disease by administering to the subject an immunologically effective amount of an immunogenic composition of the invention. In one aspect of this embodiment, the method involves treating periodontitis in a subject exhibiting symptoms of periodontitis. In another aspect of this embodiment, the method involves reducing the risk of periodontitis developing in a subject, who may have a predisposition to developing periodontitis, including moderate to severe periodontitis, where the predisposition is associated with a risk factor such as age, genetic predisposition, an immunocompromised state, a systemic disease that increases the risk of developing periodontitis, the presence of endodontic lesions or abscesses, or other risk factors. Examples of systemic diseases that increase the risk of developing moderate to severe periodontitis include diabetes mellitus, AIDS, leukemia, and Down's syndrome.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides the SDS-PAGE analysis of purified polypeptides Mfa1, HA1, and HA2 generated by cell-free protein synthesis.

FIG. 2 provides the serum IgG EC₅₀ values against P. gingivalis Mfa1, HA1, and HA2. Groups of animals G1-G6 served as controls or experimental groups, and serum samples were collected from animals immediately prior to oral challenge (Post-Vax; open bars) or at sacrifice (filled bars), and molecule-specific IgG EC₅₀ values were calculated from ELISA data against P. gingivalis (A) Mfa1, (B) HA1, and (C) HA2.

FIG. 3 shows the results of the experiments evaluating the effect of the periodontitis vaccine formulation on oral bone loss in vivo.

DETAILED DESCRIPTION OF THE INVENTION 1. Terminology and Definitions

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the invention pertains. Specific terminology of particular importance to the description of the present invention is defined below.

In this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, “a polypeptide” refers not only to a single polypeptide but also to a combination of two or more different polypeptides that may or may not be combined, “an adjuvant” refers to a single adjuvant as well as to two or more adjuvants that may be separate or combined in a single composition, and the like.

A “biomolecule,” also referred to herein as a “biological molecule,” is any organic molecule, whether naturally occurring, recombinantly produced, chemically synthesized in whole or in part, or chemically or biologically modified, that is, was or can be a part of a living organism. The term encompasses, for example, polypeptides, peptide fragments, amino acids, polysaccharides, lipids, and the like.

The term “polypeptide” is intended to include any structure comprised of one or more amino acids, and thus includes dipeptides, oligopeptides, polypeptides, polypeptide fragments, and proteins. The amino acids forming all or a part of a polypeptide may be any of the twenty conventional, naturally occurring amino acids, i.e., alanine (A), cysteine (C), aspartic acid (D), glutamic acid (E), phenylalanine (F), glycine (G), histidine (H), isoleucine (I), lysine (K), leucine (L), methionine (M), asparagine (N), proline (P), glutamine (Q), arginine (R), serine (S), threonine (T), valine (V), tryptophan (W), and tyrosine (Y), as well as non-conventional amino acids such as isomers and modifications of the conventional amino acids, e.g., D-amino acids, non-protein amino acids, post-translationally modified amino acids, enzymatically modified amino acids, β-amino acids, constructs or structures designed to mimic amino acids (e.g., α,α-disubstituted amino acids, N-alkyl amino acids, lactic acid, β-alanine, naphthylalanine, 3-pyridylalanine, 4-hydroxyproline, O-phosphoserine, N-acetylserine, N-formylmethionine, 3-methylhistidine, 5-hydroxylysine, and nor-leucine), and other non-conventional amino acids, as described, for example, in U.S. Pat. No. 5,679,782 to Rosenberg et al. The polypeptides described herein may include one or more non-natural amino acids bearing a functional group that enables conjugation to a secondary antigen, e.g., a polysaccharide. Polypeptides can be (a) naturally occurring, (b) produced by chemical synthesis, (c) produced by recombinant DNA technology, (d) produced by biochemical or enzymatic fragmentation of larger molecules, (e) produced by methods resulting from a combination of methods (a) through (d) listed above, or (f) produced by any other means for producing peptides, such as cell-free protein synthesis, described infra.

The terms “sequence identity,” “percent sequence homology,” and “sequence homology,” in the context of a polymeric biomolecule sequence, e.g., a polypeptide sequence, refer to two or more sequences that are the same or have a specified percentage of amino acid residues (or nucleotides, or other types of monomer units making up the polymeric biomolecule) that are the same, when compared and aligned for maximum correspondence over a given length (comparison window), as measured using a sequence comparison algorithm, e.g., BLASTP or the Smith-Waterman homology search algorithm. In the present context, the percent sequence homology may be determined over the full-length of the biomolecule or just a portion. One method for calculating percent sequence homology is the BLASTP program having its defaults set at a wordlength (W) of 3, an expectation (E) of 1 0, and the BLOSUM62 scoring matrix; see, e.g., Henikoff et al. (1989) Proc. Natl. Acad. Sci. USA 89:10915. Exemplary determination of sequence alignment and % sequence identity employs the BESTFIT or GAP programs in the GCG Wisconsin Software package (Accelrys, Madison Wis.), using the default parameters provided. If these preferred methods of calculating sequence identity give differing amounts, the method giving the higher sequence identity controls.

The term “substantially homologous” refers to a percent sequence homology over a given length (e.g., “x” amino acids of a polypeptide) of at least about 50%, thus including, for example, at least about 75%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, at least about 99%, and 100%.

“Recombinant” polypeptides refer to polypeptides produced by recombinant DNA techniques, i.e., produced from cells transformed by an exogenous DNA construct encoding the desired polypeptide. “Synthetic” polypeptides are those prepared by chemical synthesis.

As used herein, the term “immunogenic” refers to the ability of an antigen (e.g., a polypeptide), to elicit an immune response, either a humoral or cellular immune response, and preferably both. In a preferred embodiment, the subject will display either a therapeutic or protective immunological response to administration of an “effective amount” or “immunologically effective amount” of an immunogenic composition herein such that resistance to new infection will be enhanced and/or the clinical severity of the periodontal disease will be reduced. The immunological response will normally be demonstrated by alleviation or elimination of at least one symptom associated with the infection.

As used herein, when the term “purified” is used in reference to a molecule, it means that the concentration of the molecule being purified has been increased relative to the concentration of the molecule in its natural environment. The term may also refer to purification of a chemically synthesized molecule from a reaction mixture in which the molecule has been generated as a reaction product. As used herein, when the term “isolated” is used in reference to a molecule, the term means that the molecule has been removed from its native environment. For example, a polynucleotide or a polypeptide naturally present in a living organism is not “isolated,” but the same polynucleotide or polypeptide separated from the coexisting materials in its natural state is “isolated.” An isolated moiety, whether separated from a native environment or from a non-natural environment (e.g., recombinant expression, cell-free expression, chemical synthesis, etc.), is preferably are at least about 1% pure, 5% pure, 10% pure, 20% pure, 30% pure, 40% pure, 50% pure, 60% pure, 70% pure, 80% pure, 90% pure, 95% pure, or 99% pure, or they may be 100% pure. As used herein, the term “% pure” indicates the percentage of a composition that is made up of the molecule of interest, by weight.

As used herein, the term “molecular weight” of a polypeptide or other biomolecule refers to molecular weight calculated by size exclusion chromatography (SEC) combined with multiangle laser light scattering (MALS).

The term “treating” refers to therapeutic treatment by the administration of an immunogenic composition or vaccine formulation of the invention, where the object is to lessen or eliminate infection. For example, “treating” may include directly affecting, suppressing, inhibiting, and eliminating infection, as well as reducing the severity of, delaying the onset of, and/or reducing symptoms associated with an infection. Unless otherwise indicated explicitly or implied by context, the term “treating” encompasses “preventing” (or prophylaxis or prophylactic treatment) where “preventing” may refer to reducing the risk that a subject will develop an infection, delaying the onset of symptoms, preventing relapse of an infection, or preventing the development of infection.

2. Immunogenic Composition and Vaccine Formulation

In a first embodiment of the invention, an immunogenic composition is provided that includes at least one polypeptide that comprises: (a) an Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a Porphyromonas bacterium; and (b) an HA1 antigen sequence and/or an HA2 antigen sequence, wherein the HA1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from a Porphyromonas Gingipain HA1, and the HA2 antigen sequence is substantially homologous to an immunogenic amino acid sequence from a Porphyromonas Gingipain HA2. The at least one polypeptide may be a fusion protein that contains the Mfa1 antigen sequence, the HA1 antigen sequence, and the HA2 antigen sequence. The at least one polypeptide may also be a fusion protein that contains the Mfa1 antigen sequence and the HA1 antigen sequence, or a fusion protein that contains the Mfa1 antigen sequence and the HA2 antigen sequence. In a variation on such an embodiment, the at least one polypeptide may comprise a first polypeptide that includes the Mfa1 antigen sequence, and a second polypeptide that includes either or both the HA1 antigen sequence and the HA2 antigen sequence.

In a preferred embodiment, however, the at least one polypeptide in the immunogenic composition comprises two distinct polypeptides: a first polypeptide containing the Mfa1 antigen sequence and a second polypeptide containing the HA1 antigen sequence or the HA2 antigen sequence. In another preferred embodiment, the at least one polypeptide in the immunogenic composition comprises three distinct polypeptides: a first polypeptide containing the Mfa1 antigen sequence, a second polypeptide containing the HA1 antigen sequence, and a third polypeptide containing the HA2 antigen sequence.

As discussed above, the Mfa1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a Porphyromonas bacterium, the HA1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from a Porphyromonas Gingipain HA1, and the HA2 antigen sequence is substantially homologous to an immunogenic amino acid sequence from a Porphyromonas Gingipain HA2. The immunogenic sequences within these three antigens can collectively or individually be the full the full length protein or domain (i.e., Mfa1 protein, RgpA Gingipain hemagglutinin domain 1, and/or RgpA Gingipain hemagglutinin domain 2), or a portion (or fragment) of such protein or domain so long as the portion selected results in compositions that possess the ability to generate a therapeutic or prophylactic immunogenic response to a Porphyromonas bacterium infection. Usually these immunogenic portions or fragments of the full protein or domain are at least 20 amino acid residues in length. Provided the desired immunogenic properties are maintained, the length of the protein or domain sequence upon which the antigen sequence is based is a matter of design choice and can be at least 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, or 100 amino acid residues, up to and including the full-length protein or domain. The antigenic sequences comprised within the polypeptides of the present invention are, therefore, substantially homologous to these immunogenic amino acid sequences from the full-length or portion of the native protein or domain sequences (i.e., Mfa1 fimbrilin protein, RgpA Gingipain hemagglutinin domain 1, and/or RgpA Gingipain hemagglutinin domain 2). Typically, usually for reasons related to the methodology or efficiency of polypeptide production, the antigenic sequences comprised within the polypeptides of the present invention are not exact copies of the native immunogenic sequence to which they correspond. For example, an N-terminal methionyl, which may be treated as outside the antigenic sequence to calculate maximum percent identity or homology, is often present due to the addition of a start codon. Additions, deletions and substitutions (often conservative substitutions) can also occur provided useful immunogenic properties are still present in the polypeptide. It can be appreciated, therefore, that the present invention may be carried out with polypeptides comprising (either within it or in its entirety) an amino acid residue sequence representing an antigenic sequence (i.e., the Mfa1 antigen sequence, HA1 antigen sequence, or HA2 antigen sequence) that is substantially homologous to an immunogenic amino acid residue sequence found within the corresponding protein or domain, wherein the immunogenic amino acid residue sequence is either the full-length protein or domain, or a portion or fragment thereof. These immunogenic amino acid residue sequences against which the substantial homology of the antigenic sequences are measured are individually either the full-length protein or domain, or a portion thereof that is at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 60, at least 70, at least 80, at least 90, or 100 amino acid residues in length. Typically, these antigenic sequences are homologous to the immunogenic amino acid residue sequence against which the substantial homology of the antigenic sequence is measured at a level of at least 50%, at least 75%, at least 80%, at least 90%, at least 95%, at least 97%, at least 99%, or 100%. Routine testing in animals or humans can demonstrate readily whether compositions of the present invention based on portions of the full-length bacterial proteins or domains generate a therapeutic or prophylactic immunogenic response to infection by the bacteria in question.

Mfa1 fimbrilin protein is from a Porphyromonas bacterium, and the RgpA Gingipain hemagglutinin domains 1 and 2 are contained within an RgpA Gingipain protein that is also from a Porphyromonas bacterium, where the Porphyromonas bacterium may be any of various Porphyromonas species, including P. gingivalis, P. gulae, P. cangingivalis, P. gingivicanis, P. canoris, P. salivosa, and P. circumdentaria.

In a preferred embodiment, the Mfa1 fimbrilin protein is from P. gingivalis. Administration of an immunologically effective amount of a composition containing at least one polypeptide with an Mfa1 antigen sequence in this context will induce an immune response in which anti-Mfa1 antibodies are generated, disrupting one or more of the pathogenic pathways by which a P. gingivalis infection proceeds. In this embodiment, the Mfa1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a P. gingivalis bacterium, such as from the P. gingivalis Mfa1 fimbrilin protein having the amino acid of SEQ ID NO:1.

The P. gingivalis Mfa1 fimbrilin polypeptide, prepared as described in the Experimental Section, infra, contains 552 amino acids (this and following SEQ IDs include the addition of an N-terminal methionyl from a start codon used in the cell-free synthesis described below) and has a molecular weight of 60,018, with the amino acid sequence of SEQ ID NO: 1 reproduced for convenience below:

MGNGPDPDNAAKSYMSMTLSMPMGSARDGQNQDNPQYNFVGEWAGK DKIEKVSIYMVPQGGPGLVESAEDLDEGTYYDAPTQEAGSNNVILK PKKGIKVNSAVGKTVKVYVVLNDIAGKAKALLANVNAVDFEAKFKE VIELSTQAQALGTVADGPNPATAAGKIAKKNGVDNETIMMTCFEPS APLTIEAAVSEANAIAGVKNQAKVTVERSVARAMVSTKAESYEIKA TTQIGSIAAGDVLATVSDIRWVVAQGERKQYLSKKRGTVPENTWVT PGSDYISTNANFHAQATMYYDYTGLWDDHNADPTMVSGTKVPTLAN YQLQDVTDELAQRLSGKFLLPNTHKSGIDAATSHYKRGNTAYVLVR AKFTPKKEAFIDKGKDYTDGTPVPEYTDGDDFFVGENGQFYVSMKS VTDPKVGGVAGMKAHKYVKGKVLYYAWLNPSTTSPDSWWNSPVVRN NIYHIHIKSIKKLGFNWNPLVPNPQNPNDPNGPINPNNPDPNPDEP GTPIPTDPEQPLPDQDTFMSVEVTVLPWKVHSYEVDL

In this embodiment, in which the Mfa1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein from P. gingivalis, it is preferred, although not essential, that the HA1 antigen sequence be substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 1 (HA1) contained within a P. gingivalis RgpA Gingipain protein, where, for example, the immunogenic amino acid sequence may be from the HA1 having SEQ ID NO: 2. Analogously, it is preferred, in this embodiment, that the HA2 antigen sequence be substantially homologous to an immunogenic amino acid sequence from an RgpA Gingipain hemagglutinin domain 2 (HA2) contained within a P. gingivalis RgpA Gingipain protein, where the immunogenic amino acid sequence may be from the HA2 having SEQ ID NO:3.

P. gingivalis Gingipain HA1, prepared as described infra, contains 176 amino acids and has a molecular weight of 19,059, with the amino acid sequence of SEQ ID NO: 2 reproduced for convenience below:

MLSESFENGIPASWKTIDADGDGHGWKPGNAPGIAGYNSNGCVYSE SFGLGGIGVLTPDNYLITPALDLPNGGKLTFWVCAQDANYASEHYA VYASSTGNDASNFTNALLEETITAKGVRSPEAIRGRIQGTWRQKTV DLPAGTKYVAFRHFQSTDMFYIDLDEVEI

P. gingivalis Gingipain HA2, also prepared as described infra, contains 442 amino acids and has a molecular weight of 48,299, with the amino acid sequence of SEQ ID NO: 3, reproduced below:

MFTETFESSTHGEAPAEWTTIDADGDGQDWLCLSSGQLDWLTAHGG TNVVASFSWNGMALNPDNYLISKDVTGATKVKYYYAVNDGFPGDHY AVMISKTGTNAGDFTVVFEETPNGINKGGARFGLSTEANGAKPQSV WIERTVDLPAGTKYVAFRHYNCSDLNYILLDDIQFTMGGSPTPTDY TYTVYRDGTKIKEGLTETTFEEDGVATGNHEYCVEVKYTAGVSPKV CVNVTINPTQFNPVKNLKAQPDGGDVVLKWEAPSGKRGELLNEDFE GDAIPTGWTALDADGDGNNWDITLNEFTRGERHVLSPLRASNVAIS YSSLLQGQEYLPLTPNNFLITPKVEGAKKITYKVGSPGLPQWSHDH YALCISKSGTAAADFEVIFEETMTYTQGGANLTREKDLPAGTKYVA FRHYNCTDVLGIMIDDVVI

Combining the Mfa1 antigen sequence with either or both the HA1 antigen sequence and the HA2 antigen sequence in one or more polypeptides in a single immunogenic composition is believed to target multiple mechanisms involved in the pathogenic progression of periodontal disease associated with Porphyromonas infection, i.e., mechanisms associated with the Mfa1 fimbrilin protein as well as the RgpA gingipain proteins.

In another embodiment, the Mfa1 fimbrilin protein is from P. gulae. In this case, the Mfa1 antigen sequence is substantially homologous to an immunogenic amino acid sequence from an Mfa1 fimbrilin protein of a P. gulae bacterium, such as from the P. gulae Mfa1 fimbrilin protein having the amino acid of SEQ ID NO:4. As explained with respect to P. gingivalis, the HA1 antigen sequence and the HA2 antigen sequence should be substantially homologous to immunogenic amino acid sequences from an RgpA hemagglutinin domain 1 and an RgpA hemagglutinin domain 2, respectively, contained within an RgpA Gingipain protein of a P. gulae organism. The immunogenic amino acid sequence from the P. gulae HA1 may be from SEQ ID NO: 5, and the immunogenic amino acid sequence from the P. gulae HA2 may be from SEQ ID NO: 6.

P. gulae Mfa1 fimbrilin polypeptide  (SEQ ID NO: 4): MGNGPDPDNAAKSYMSMTLSMPLGSARAGDGQDQPNPDYNYVGEWA GKDKIEKVSIYMVPQGGPGLVESAEDLDFSTYYDAPTQDPGSNNVI LKPKKGIKVNSAVGKTVKVYVVLNDIAGKAKALLANVNAADFDAKF KEVIELSTQAEAVSQANAFNGTAAGKIAKKNGATDETIMMTCLQPS DALTIEAAVSEANAIAGVKNQAKVTVERSVARAMLSTKADTFEILA ANQIGEIAAGSVLATITDIRWVVAQGERRQYLSKKRGTIQENTWVT PGSDFVPTSSTFHTNATEYYDYAGWEDHNTDPTVISGTQVPTLADY QLQNVTDELAQSLSGKFLLPNTHKSGTDAATSHYKRGNTAYVLIRA KFTPKKEAFIDKGKTYTDGTQVPEYEADQDFFVGENGQFYVSMKSV TDPKVGGVTGMKAHKYVKGKVLYYAWLNPSTTSPDTWWNSPVVRNN IYHIHIKSIKKLGFNWNPLVPDPNPNDPVNPNNPDPNPDEPGTPVP TDDPEQPLPDQDTFMSVEVTVLPWKVHSYEVDL P. gulae Gingipain HA1 (SEQ ID NO: 5): MTESFDGGIPATWTLIDADGDGHGWKHGKAPGVAGYNSNGCVYSES FGLGGIGVLTPDNYLITPALNLPNGGKLTFWVCAQDAAYASEHYAV YASSTGNAASNFTNALLEETLTAKGVRSPEAIRGRVQGTWYQKTVD LPAGTKYVAFRHFQSTDMFYIDIDEVEI P. gulae Gingipain HA2 (SEQ ID NO: 6): MNAKRSELLNENFEGDDIPAGWTALDADGDGNNWGVQLNQFTRGER EALAPLRASNVAISYSSLNQGGGYLPLTPNNFLITPKVEGAKKISY KVGSPGNQSWSHDHYALCISKTGTAASDFEIIFEETMVYSQGGANF TREKDLPDGTKYVAFRHYNCTDVLAIVIDDVVITG

The present immunogenic compositions thus include:

(1) an immunogenic composition comprising (a) a P. gingivalis Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Mfa1 fimbrilin protein having SEQ ID NO: 1, and (b) a P. gingivalis HA1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Gingipain HA1, SEQ ID NO: 2;

(2) an immunogenic composition comprising (a) a P. gingivalis Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Mfa1 fimbrilin protein having SEQ ID NO: 1, and (b) a P. gingivalis HA2 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Gingipain HA2, SEQ ID NO: 3;

(3) an immunogenic composition comprising (a) a P. gingivalis Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Mfa1 fimbrilin protein having SEQ ID NO: 1, (b) a P. gingivalis HA1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Gingipain HA1, SEQ ID NO: 2, and (c) a P. gingivalis HA2 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gingivalis Gingipain HA2, SEQ ID NO: 3;

(4) an immunogenic composition comprising (a) a P. gulae Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Mfa1 fimbrilin protein having SEQ ID NO: 4, and (b) a P. gulae HA1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Gingipain HA1, SEQ ID NO: 5;

(5) an immunogenic composition comprising (a) a P. gulae Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Mfa1 fimbrilin protein having SEQ ID NO: 4, and (b) a P. gulae HA2 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Gingipain HA1, SEQ ID NO: 6; and

(6) an immunogenic composition comprising (a) a P. gulae Mfa1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Mfa1 fimbrilin protein having SEQ ID NO: 4, (b) a P. gulae HA1 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Gingipain HA1, SEQ ID NO: 5, and (c) a P. gulae HA2 antigen sequence that is substantially homologous to an immunogenic amino acid sequence from P. gulae Gingipain HA1, SEQ ID NO: 6.

In a preferred embodiment, the composition comprises an immunogenic composition suitable for incorporation into a vaccine formulation. At least one polypeptide containing a selected antigen sequence, as described above, is preferably incorporated into the composition in isolated or purified form, where the terms “isolated” and “purified” are defined earlier herein. The amount of the at least one polypeptide in the immunogenic composition is a sufficient and effective amount to generate a therapeutic or prophylactic immune response in a subject, i.e., an amount rendering the composition as a whole immunogenic. Thus, administration of an immunologically effective dose of the immunogenic composition to a subject, in a vaccine formulation, will elicit an immune response as explained in part (I) of this section, preferably a response that serves to inhibit the progression of, or prevent the onset of, periodontal disease associated with a Porphyromonas infection. The relative amounts of each polypeptide in the composition may vary a great deal. However, the composition is generally formulated with the selected polypeptides—for example, (a) a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA1 antigen sequence, the HA2 antigen sequence, or both; or (b) a first polypeptide comprising the Mfa1 antigen sequence, a second polypeptide comprising the HA1 antigen sequence, and a third polypeptide comprising the HA2 antigen sequence—combined in amounts corresponding to a weight ratio of each polypeptide in the composition to each other polypeptide in the composition in the range of about 1:5 to about 5:1, typically in the range of about 1:3 to about 3:1, for example in the range of about 1:1.5 to about 1.5:1, including about 1:1. In a preferred embodiment, the weight ratio of each polypeptide in the composition to each other polypeptide in the composition is in the range of 1:5 to 5:1, typically 1:3 to 3:1, such as 1:1.5 to 1.5:1, and including 1:1. Accordingly, the immunogenic composition may be one of the following:

(1) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA1 antigen sequence in a weight ratio ranging from 1:5 to 5:1;

(2) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA1 antigen sequence in a weight ratio ranging from 1:3 to 3:1;

(3) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA1 antigen sequence in a weight ratio ranging from 1:1.5 to 1.5:1;

(4) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA1 antigen sequence in a weight ratio of about 1:1;

(5) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA2 antigen sequence in a weight ratio ranging from 1:5 to 5:1;

(6) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA2 antigen sequence in a weight ratio ranging from 1:3 to 3:1;

(7) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA2 antigen sequence in a weight ratio ranging from 1:1.5 to 1.5:1;

(8) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence and a second polypeptide comprising the HA2 antigen sequence in a weight ratio of about 1:1;

(9) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence, a second polypeptide comprising the HA1 antigen sequence, and a third polypeptide comprising the HA2 antigen sequence, wherein the weight ratio of each polypeptide in the composition to each other polypeptide in the composition is in the range of 1:5 to 5:1;

(10) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence, a second polypeptide comprising the HA1 antigen sequence, and a third polypeptide comprising the HA2 antigen sequence, wherein the weight ratio of each polypeptide in the composition to each other polypeptide in the composition is in the range of 1:3 to 3:1;

(11) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence, a second polypeptide comprising the HA1 antigen sequence, and a third polypeptide comprising the HA2 antigen sequence, wherein the weight ratio of each polypeptide in the composition to each other polypeptide in the composition is in the range of 1:1.5 to 1.5:1; and

(12) a composition formulated by combining a first polypeptide comprising the Mfa1 antigen sequence, a second polypeptide comprising the HA1 antigen sequence, and a third polypeptide comprising the HA2 antigen sequence, wherein the weight ratio of each polypeptide in the composition to each other polypeptide in the composition is about 1:1, such that the weight ratios of the three polypeptides are about 1:1:1.

Additional antigens: In addition to the at least one polypeptide comprising the Mfa1 antigen sequence and the HA1 antigen sequence and/or the HA2 antigen sequence, the immunogenic composition may contain one or more additional antigens. An additional antigen may be one that induces an antibody response that targets Porphyromonas pathogenic mechanisms and/or virulence factors, for example, the bacterial tyrosine kinase Ptk1 (see Bainbridge (2010) Infect. Immun. 78(11): 4560-69) or the phosphoserine phosphatase enzyme SerB (see Wright et al. (2014) (MicrobiologyOpen 3(3): 383-94. Antigens may also be included in the composition that are directed toward pathogens other than Porphyromonas organisms, such as organisms that tend to be present in the multimicrobial biofilm associated with the progression of periodontal disease.

The at least one polypeptide of the immunogenic composition can be prepared in many ways, e.g., by solid phase or liquid phase chemical synthesis (in whole or in part), by digestion of longer polypeptides using proteases, by cell-based recombinant protein expression, by purification from a cell culture (e.g. from recombinant expression), etc. A preferred method for preparing the polypeptides, however, is the scalable cell-free protein synthesis (“CFPS”) system, described in U.S. Pat. No. 9,040,253 to Roy et al., U.S. Pat. No. 9,650,621 to Thanos et al., and Murray et al. (2013) Current Opin. Chem. Biol. 17(3): 420-26, all of which are incorporated by reference herein. Cell-free synthesis of the Mfa1, HA1, and HA2 polypeptide antigens is described in detail in the Examples below.

The invention also provides a vaccine formulation that comprises the immunogenic composition in a sterile formulation for administration to a subject, e.g., as a suspension, solution or in lyophilized form to be rehydrated prior to use. The vaccine formulation includes the at least one polypeptide comprising the Mfa1 antigen sequence and the HA1 antigen sequence and/or the HA2 antigen sequence; optional additional antigens as explained above; and at least one additional component selected from adjuvants and excipients, as follows:

Adjuvants: The vaccine formulation may contain one or more adjuvants to potentiate the immune response to one or more antigens in the immunogenic composition. Suitable vaccine adjuvants for incorporation into the present formulation are described in the pertinent texts and literature and will be apparent to those of ordinary skill in the art. The major adjuvant groups are as follows:

Mineral salt adjuvants, including alum-based adjuvants such as aluminum phosphate, aluminum hydroxide, and aluminum sulfate, as well as other mineral salt adjuvants such as the phosphate, hydroxide, and sulfate salts of calcium, iron, and zirconium;

Saponin formulations, including the Quillaia saponin Quil A and the Quil A-derived saponin QS-21, as well as immune stimulating complexes (ISCOMs) formed upon admixture of cholesterol, phospholipid, and a saponin;

Bacteria-derived and bacteria-related adjuvants, including, without limitation, cell wall peptidoglycans and lipopolysaccharides derived from Gram negative bacteria such as Mycobacterium spp., Corynebacterium parvum, C. granulosum, Bordetella pertussis, and Neisseria meningitis, such as Lipid A, monophosphoryl Lipid A (MPLA), other Lipid A derivatives and mimetics (e.g., RC529), enterobacterial lipopolysaccharide (“LPS”), TLR4 ligands, and trehalose dimycolate (“TDM”);

Muramyl peptides such as N-acetyl muramyl-L-alanyl-D-isoglutamine (“MDP”) and MDP analogs and derivatives, e.g., threonyl-MDP and nor-MDP;

Oil-based adjuvants, including oil-in-water (O/W) and water-in-oil (W/O) emulsions, such as squalene-water emulsions (e.g., MF59, AS03, AF03), complete Freund's adjuvant (“CFA”) and incomplete Freund's adjuvant (“IFA”);

Liposome adjuvants;

Microsphere adjuvants formed from biodegradable and non-toxic polymers such as a poly(α-hydroxy acid), a poly(hydroxy butyric) acid, a polyorthoester, a polyanhydride, a polycaprolactone, etc.;

Human immunomodulators, including cytokines, such as interleukins (e.g. IL-1, IL-2, IL-4, IL-5, IL-6, IL-7, IL-12), interferons (e.g. interferon-γ), macrophage colony stimulating factor, and tumor necrosis factor;

Bioadhesives and mucoadhesives, such as chitosan and derivatives thereof and esterified hyaluronic acid and microspheres or mucoadhesives, such as cross-linked derivatives of poly(acrylic acid), polyvinyl alcohol, polyvinyl pyrrolidone, polysaccharides and carboxymethylcellulose;

Imidazoquinolone compounds, including Imiquamod and homologues thereof, e.g., Resiquimod;

TLR-9 agonists, such as Hsp90 and oligodeoxynucleotides containing unmethylated CpG motifs (see, e.g., Bode et al. (2011) Expert Rev. Vaccines 10(4): 499-511); and

Carbohydrate adjuvants, including the inulin-derived adjuvants gamma inulin and algammulin, and other carbohydrate adjuvants such as polysaccharides based on glucose and mannose, including glucans, dextrans, lentinans, glucomannans, galactomannans, levans, and xylans.

Exemplary adjuvants herein include alum-based salts such as aluminum phosphate and aluminum hydroxide.

The vaccine formulation also includes at least one excipient, and usually two or more excipients, to serve any of a number of functions, where the excipients are immunologically and pharmacologically inert components that are “pharmaceutically acceptable.” A “pharmaceutically acceptable” component herein is one that (1) can be included in a vaccine formulation administered to a subject without causing significant unwanted biological effects or interacting in a deleterious manner with any of the other components of the formulation; and (2) meets the criteria set out in the Inactive Ingredient prepared by the U.S. Food and Drug Administration, and, preferably, has also been designated “Generally Regarded as Safe” (“GRAS”). The type of excipient or excipients incorporated into a vaccine formulation herein will depend, in part, on the selected mode of administration and the particular formulation type or dosage form, e.g., injectable liquid formulations, intranasal spray formulations, or the like; modes of administration and corresponding formulations are discussed infra. In general, however, inert components that can be advantageously incorporated into the vaccine formulation of the invention include, without limitation, vehicles, solubilizers, emulsifiers, stabilizers, preservatives, isotonicity agents, buffer systems, dispersants, diluents, viscosity modifiers, absorption enhancers, and combinations thereof. A thorough discussion of pharmaceutically acceptable inert additives is available in Gennaro (2000) Remington: The Science and Practice of Pharmacy. 20th ed., ISBN: 0683306472.

3. Administration and Use

The immunogenic composition of the invention is useful in a method for immunizing a subject against periodontal disease, where the method involves administering to the subject an immunologically effective amount of a periodontal vaccine formulation comprising an immunogenic composition as described herein.

The subject may be a human or a non-human mammal, and the selection of target bacterium (which will be the source of the immunogenic amino acid sequences to which the antigen sequences correspond) may depend on the type of subject. For example, an immunogenic composition according to the present invention used to treat or prevent periodontitis in a human subject will typically be targeted to P. gingivalis. As another example, an immunogenic composition according to the present invention used to treat or prevent periodontitis in a non-human mammal, where such subjects may be dogs, horses, dairy cattle, cats, or other mammals, will generally be targeted to P. gulae.

The method may involve administration of the immunogenic composition as a therapeutic vaccine, i.e., to treat a subject suffering from periodontitis. The method may also involve administration of the immunogenic composition as a prophylactic vaccine, meaning that, for example, the method reduces the risk of periodontitis (including moderate to severe periodontitis) developing in a subject and thus may postpone or eliminate development of periodontitis. When the vaccine is used prophylactically, the subject may be predisposed to developing periodontitis as a result of any number of risk factors, including age; a genetic predisposition; an immunocompromised state; a disease that increases the risk of developing moderate to severe periodontitis, such as diabetes mellitus, AIDS, leukemia, Down's syndrome; or the presence of endodontic lesions or abscesses. As an example, patients receiving anti-TNF therapy (i.e., taking a TNF inhibitor such as etanercept or adalimumab), such as in the treatment of rheumatoid arthritis or psoriasis, often exhibit gingival inflammation and have an elevated risk of developing periodontitis.

The “immunologically effective amount” of the vaccine formulation is an amount that, either as a single dose or as part of a series of two or more doses, is effective for treating or preventing periodontal disease, where “treating” and “preventing” are defined in part (1) of this section. The amount administered will vary according to several factors, including the overall health and physical condition of the subject, the subject's age, the capacity of the subject's immune system to synthesize relevant antibodies, the form of the composition (e.g., injectable liquid, nasal spray, etc.), the taxonomic group of the subject (e.g., human, non-human primate, non-primates, etc.), and other factors known to the medical practitioner overseeing administration.

Administration of the immunogenic composition as a vaccine formulation can be carried out using any effective mode of systemic delivery. The composition is usually administered parenterally, such as by injection, including intravenous, intramuscular, intraperitoneal, interstitial, or subcutaneous injection; injection may also be gingival, in which case the vaccine formulation is injected directly into the gum. The composition may, in addition, be administered transmucosally, such as via the intranasal, sublingual, transbuccal, intravaginal, or intrarectal routes. Other modes of administration are also envisioned, however, and the invention is not limited in this regard. By way of example, other modes of administration include oral and transdermal delivery as well as administration via inhalation or using a subdermal implant.

The mode of administration largely dictates the type of formulation or dosage form that comprises the immunogenic composition. Compositions formulated for parenteral administration include sterile aqueous and nonaqueous solutions, suspensions, and emulsions. Injectable aqueous solutions contain the active agent in water-soluble form. Examples of nonaqueous solvents or vehicles include fatty oils, such as olive oil and corn oil, synthetic fatty acid esters, such as ethyl oleate or triglycerides, low molecular weight alcohols such as propylene glycol, synthetic hydrophilic polymers such as polyethylene glycol, liposomes, and the like. Parenteral formulations may also contain excipients such as solubilizers, emulsifiers, stabilizers, preservatives, isotonicity agents, buffer systems, dispersants, diluents, viscosity modifiers, absorption enhancers, and combinations thereof. Injectable formulations are rendered sterile by incorporation of a sterilizing agent, filtration through a bacteria-retaining filter, irradiation, or heat. They can also be manufactured using a sterile injectable medium. The immunogenic composition or individual components thereof may also be in dried, e.g., lyophilized, form that may be rehydrated with a suitable vehicle immediately prior to administration via injection.

Of the transmucosal routes, intranasal administration is generally although not necessarily preferred. Intranasal formulations, including intranasally administered vaccine formulations, are known in the art, and should be formulated with reference to the FDA's Guidance for Industry: Nasal Spray and Inhalation Solution, Suspension, and Spray Drug Products. Intranasal formulations are liquids, i.e., solutions, emulsions, suspensions, or the like, for administration as sprays, intranasal injections, or drops, and can contain adjuvants and pharmaceutically acceptable excipients as above. Because of the relatively large size of the antigens in the formulation, systemic delivery via the intranasal route requires incorporation of a transmucosal absorption enhancer in the immunogenic composition. Examples of suitable transmucosal absorption enhancers include, without limitation, alkylsaccharides, cyclodextrins, and chitosans; see Maggio (2014) J. Excip. Food Chem. 5(2): 100-12; and Merkus et al. (1999) Adv. Drug Deliv. Rev. 36: 41-57. The concentration of enhancer is selected to ensure that an immunologically effective amount of the formulation passes through the nasal membrane and into the systemic circulation at an efficient transport rate. Various anatomical and physiological considerations dictating the composition and nature of an intranasal vaccine formulation are discussed, for example, by Aurora (October 2002) Drug Development & Delivery 2(7), incorporated by reference herein.

Other modes of administration and corresponding formulations include, without limitation: sublingual administration with a rapidly dissolving dosage form such as a rapidly dissolving tablet; transbuccal administration using a buccal patch or other buccal delivery system; intravaginal administration using a pessary, ointment, or cream; intrarectal delivery using a rectal suppository, ointment, or cream; transdermal administration using a transdermal patch or formulation; subdermal administration with an injected implant or pellet; inhalation using a dry powder pulmonary formulation; and oral administration using an oral dosage form such as a tablet, capsule, or the like.

As alluded to earlier herein, the vaccine formulation is administered to a subject within the context of an appropriate dosage regimen. The composition may be administered once, or two or more times spaced out over an extended time period. For example, an initial, “prime” dose may be followed by at least one “boost” dose. The time interval between the prime and the subsequent boost dose, and between boost doses, is usually in the range of about 2 to about 24 weeks, more typically in the range of about 2 to 12 weeks, such as 2 to 8 weeks, 3-6 weeks, etc. Regardless of the mode of administration, e.g., intramuscular injection, gingival injection, intranasal administration, or the like, the volume of a single dose of the vaccine will generally be in the range of about 1 μL to about 500 μL, typically in the range of about 1 μL to about 250 μL, more typically in the range of about 2.5 μL to about 200 μL, and preferably in the range of about 5 μL to about 150 μL. It will be appreciated that the concentration of total antigen in the immunogenic composition corresponds to an immunologically effective dose of the composition per unit volume, working from the aforementioned dose volume guidelines.

For ease of use, the immunogenic composition of the invention can be incorporated into a packaged product, or “kit,” including instructions for self-administration or administration by a medical practitioner. The kit includes a sealed container housing a dose of the vaccine formulation, typically a “unit dose” appropriate for a single dosage event that is immunologically effective. The vaccine may be in liquid form and thus ready to administer as an injection or the like, or it may be in another form that requires the user to perform a preparation process prior to administration, e.g., hydration of a lyophilized formulation, activation of an inert component, or the like. The kit may also include two or more sealed containers with the prime dose in a first container and a boost dose in one or more additional containers, or a periodontitis vaccine formulation in a first container and a vaccine directed against another infection, which may or may not be related to the Porphyromonas infection, in another container.

It is to be understood that while the invention has been described in conjunction with a number of specific embodiments, the foregoing description as well as the experimental section that follows are intended to illustrate and not limit the scope of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention, the description taken with the drawings and/or examples making apparent to those skilled in the art how the invention may be embodied in practice. This disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the elements of the invention described herein are encompassed by the disclosure unless otherwise indicated herein or clearly contradicted by context.

EXPERIMENTAL

Generation of Cell Free Extract:

Cell free extracts containing additional DsbC chaperone were prepared as previously described by Groff et al. (2014) Mabs 7(1):231-242. Briefly, E. coli strain SBJY001 (see Yin et al. (2012) Mabs 6(3):671-678) was transformed with a pACYC plasmid carrying tandem copies of the dsbC gene. Cells were grown, harvested and homogenized as described by Zawada et al. (2011) Biotechnol. Bioeng. 108(7):1570-1578. Subsequent clarification via centrifugation yielded the extract used for subsequent cell free expression reaction.

Generation of Recombinant P. gingivalis Mfa1, HA1, HA2, and purification: DNA sequences encoding the HA1, HA2 and Mfa1 fimbrilin proteins associated with P. gingivalis were codon optimized, synthesized (DNA 2.0; Menlo Park, Calif.) and cloned into the previously described pYD317 vector [30]. Cell-free reactions were performed with the Xpress CFTM CFPS system essentially as previously described (Yin et al., supra; Zimmerman et al. (2014) Bioconjug. Chem. 25(2):351-361). For expression of HA1, HA2, and Mfa1 fimbrilin, reactions were performed with IAM pre-treatment, at 25° C., with the addition of oxidized glutathione (2 mM) to create an oxidizing environment for the disulfide bonds. Expression of HA1 and HA2 was performed without IAM treatment of the cell extract; addition of reduced glutathione (8 mM) maintained a reducing expression environment. After 16 h of reaction time, the expressed proteins were isolated from the cell-free reaction mixtures using his-tag affinity purification on Ni Sepharose resin (GE Lifesciences, Pittsburg, Pa.) per the manufacturer's recommendations. Further purification of the HA1, HA2, as well as Mfa1 fimbrilin protein was achieved via cation exchange chromatography on SP ImpRes resin (GE Lifesciences). Briefly, the Ni Sepharose elution pools were exchanged into sodium citrate (50 mM), NaCl (50 mM), pH 4.5, and applied to a column equilibrated in the same buffer. Polished protein was subsequently eluted via gradient elution to Tris (50 mM), NaCl (1 M), pH 7.5. Similarly, HA2 was further purified via anion exchange chromatography on Q ImpRes (GE Lifesciences). Column equilibration and loading was performed in Tris (50 mM), NaCl (50 mM), pH 7.5, with subsequent gradient elution to Tris (50 mM), NaCl (1M), pH 7.5.

After polishing chromatography, all proteins were dialyzed into Dulbecco's PBS and analyzed via SDS-PAGE. and intact mass analysis via Q-TOF (Agilent, Santa Clara, Calif.). In the case of HA1, intact mass analysis conclusively showed that the cysteines were oxidized and had formed the expected disulfide bond.

Cultivation of P. gingivalis and Bacterial Purity Assessment:

Porphyromonas gingivalis strain A7436 was handled as described previously (Huang et al. (2015) Mol. Oral. Microbiol. 30(6):438-450). In brief, freezer stocks were plated on anaerobic blood agar plates, P. gingivalis were collected after three days of anaerobic growth at 37° C., harvested organisms were placed into sterile brain-heart infusion broths supplemented with L-cysteine (0.75 g/L), hemin (5 mg/L), and menadione (1 mg/L). After 24 h, bacteria in log-phase growth were harvested by centrifugation and suspended to 1×1010 CFU/mL in 2% carboxymethylcellulose in pyrogen-free saline for oral challenge (100 μL/challenge). For immunizations, broth grown P. gingivalis were adjusted to 1×109 CFU/mL in injection-grade saline, and heat-killed (60° C. for 30 min.) prior to injection, and bacterial kill was confirmed by plating. Gram-staining was performed on all P. gingivalis broth cultures to ensure purity.

Mice, Immunizations, and Oral Challenge:

Six-week old female BALB/c mice (Charles River Laboratories, Wilmington, Mass.), were randomly separated into six groups (n=8/group), were housed in specific pathogen free facilities, and received water and food ad libitum. All live animal use was performed in accordance with IACUC approvals. Groups included G1) non-immunized/no oral challenge control, G2) non-immunized/P. gingivalis oral challenge, G3) heat-killed P. gingivalis immunization/P. gingivalis oral challenge, G4) Mfa1+HA1+HA2 combined immunization in alum/P. gingivalis oral challenge, G5) Mfa1+HA1+HA2 combined immunization in MPL/P. gingivalis oral challenge, and G6) Mfa1+HA1+HA2 combined immunization in injection-grade saline/P. gingivalis oral challenge. Prior to initiation of immunizations, baseline serum samples were obtained from each animal, and then respective groups of mice were immunized by intramuscular injection of killed P. gingivalis, or Mfa1+HA1+HA2 (5 μg of each protein/injection) suspended in either alum (Imject, ThermoFisher Sci, Rockford, Ill.), monophosphoryl lipid A (MPL; Sigma-Aldrich, St. Louis, Mo.), or injection-grade saline. Subsequent intramuscular booster immunizations were delivered 2-, and 4-weeks after the initial immunization. Two-weeks after completion of immunization, a serum sample was obtained from animals immediately prior to oral challenge with P. gingivalis. Oral challenge of mice was accomplished as reported previously (Gonzalez et al. (2003) Infect. Immun. 71(4):2283-2287). In brief, animals received 10-day oral sulphamethoxazole/trimethoprim (Hi-Tech Pharmical, Amityville, N.Y.) in drinking water, followed by removal of antibiotics and a three-day rest. A P. gingivalis slurry (1×1010 CFU/ml+2% carboxymethylcellulose in injection-grade saline) was gently applied to the gums of challenged mice using a syringe fitted with a feeding needle 3-times over a 1-week period. Control animals included those that were mock challenged with 2% carboxymethylcellulose alone. After a 42-day rest following completion of oral challenge, animals were sacrificed, terminal bleeds were obtained, and the head of each mouse was processed for oral bone loss measurements. A final serum sample was collected from each animal at sacrifice, and all serum samples collected were stored at −80° C.

Detection of Mfa1-, HA1-, and HA2-Specific IgG in Mouse Sera:

Antigens (0.5 μg/mL) were plated at 4° C. overnight on Maxisorp plates (NUNC, Rochester, N.Y.), washed three times with PBS containing Tween-20 (0.05%), and blocked with PBS with 1% BSA for a minimum of 1 h. Serial 2-fold diluted serum samples from vaccinated mice (100 μL/well) were added to individual wells and incubated for 2 h at room temperature. Plates were washed, incubated with appropriate isotype specific antibody conjugated to horseradish peroxidase (1:6000 dilution; Southern Biotech, Birmingham, Ala.), visualized with the addition of 100 μL of TMB substrate (Pierce, Rockford, Ill.) for 20-30 min, and reaction stopped by the addition of 50 μL H2SO4 (1.0 M). Absorbance in each well was measured at 450 nm minus the absorbance at 570 nm to correct for plate abnormalities. The resulting data for each sample were plotted to obtain a curve of the reciprocal dilution versus the A450-A570 measurement. The antibody titer was determined as the midpoint of the dilution curve as defined by EC50 calculations using Prism statistical analysis software (GraphPad Software, La Jolla, Calif.). The mean of the EC50 for each cohort was determined to be the final antibody titer.

Measurement of Oral Bone Loss:

Oral bone levels were determined by morphometric analyses, as done previously (Gibson et al. (2001) Infect. Immun. 69(12): 7959-7963). After sacrifice, soft tissue was removed around the maxillary molars, and following extensive cleaning, the skulls were stained with methylene blue. Prior to initiation of bone measurements, samples were blinded by a researcher not aware of the groupings. Oral bone measurements at the maxillary molars were obtained using a digital camera affixed to a stereomicroscope from the alveolar bone crest (ABC) to the cementum enamel junction (CEJ) at 14 landmark sites (Baker et al. (1994) Arch. Oral Biol. 39(12): 1035-1040). Image analysis was performed using ImageJ (Schneider et al. (2012) Nat. Methods 9(7): 671-675) and onscreen pixel lengths were converted to millimeters, and data obtained from each animal in a group were combined to achieve a group level mean length±SEM.

Statistical Analysis:

Data were analyzed with Prism statistical analysis software (GraphPad). Comparison between groups was performed as indicated using unpaired Student T test, or ANOVA with post-test analysis, and P<0.05 was considered significant.

Results:

SDS-PAGE: The purified proteins generated by CFPS were denatured and added to wells (3 μg/well), separated on 4-12% Bis-Tris gradient gels, and stained with coomassie blue. Results of the analysis of the proteins generated under reducing conditions are shown in FIG. 1 . Lane 1: molecular mass markers. Lane 2: Mfa1. Lane 3: HA1. Lane 4: HA2.

To determine whether the proteins delivered by intramuscular injection elicited protein-specific IgG antibody responses, and to determine whether different adjuvants (alum vs. MPL) influenced the elicited IgG response, sera were collected from groups of mice at the completion of the immunization period, and at sacrifice were tested for levels of Mfa1-, HA1- and HA2-specific IgG by ELISA. Titration curves for each serum sample were converted to EC₅₀ values. As anticipated, sera collected from the non-immunized group of mice prior to oral challenge possessed low levels of IgG to Mfa1, HA1, and HA2. Sera collected from mice immunized with killed P. gingivalis A7436 elicited a nominal increase in IgG specific to purified Mfa1, and HA2, with HA2>Mfa1. For the groups of mice immunized IM with the combined proteins suspended in alum, MPL, or injection-grade saline revealed that all mice receiving the vaccine combination responded with antigen-specific IgG responses. Post-immunization levels of IgG to Mfa1 was most robust in MPL adjuvant; MPL>alum or saline. For HA1, alum best facilitated molecule-specific IgG with alum>MPL>saline, while for HA2 alum and MPL facilitated antigen-specific IgG responsivity to similar levels and were both greater than that observed with saline.

Comparisons of IgG levels at sacrifice, revealed that the group of non-immunized mice oral challenged with P. gingivalis A7436 generated slight elevation in specific IgG to Mfa1 and HA2, but not against HA1. Immunization with heat-killed P. gingivalis A7436 revealed a similar low-level increase in in comparison to levels of IgG measured immediately prior to oral challenge, independent of adjuvant or saline, with the exception of measured IgG against HA1 from mice immunized with the protein combination in saline.

FIG. 2 provides the serum IgG EC₅₀ values against P. gingivalis Mfa1, HA1, and HA2. Groups of animals G1-G6 served as controls or experimental groups, and serum samples were collected from animals immediately prior to oral challenge (Post-Vax; open bars) or at sacrifice (filled bars), and molecule-specific IgG EC₅₀ values were calculated from ELISA data against P. gingivalis (A) Mfa1, (B) HA1, and (C) HA2.

To understand if the protein combination could effectively limit the extent of P. gingivalis elicited oral bone loss, immunized animals were subjected to P. gingivalis oral challenge. Groups of mice that were not immunized, or immunized with killed P. gingivalis served as controls. In comparison to mock challenged mice (G1), animals orally challenged with P. gingivalis A7436 (G2) developed oral bone loss as evidenced by an increase in mean distance from ABC to CEJ (p<0.001). As anticipated, immunization with the killed preparation of P. gingivalis A7436 (G3) provided measurable protection from homologous organism-elicited oral bone loss (p<0.01). Groups of mice that received the combination protein vaccine generated from a heterologous strain of P. gingivalis suspended in either alum (G4) or MPL (G5) were protected from P. gingivalis-elicited oral bone loss (p<0.01 for each vs. P. gingivalis oral challenge alone. No differences in the level of protection (ABC to CEJ measurements) was observed between adjuvants, indicating that intramuscular delivery of the vaccine candidate provided similar protective responses (p>0.05). It was also observed that the group of animals immunized with the combination protein vaccine suspended in saline solution (G6) were also protected from P. gingivalis oral challenge similar to that observed when the proteins were delivered intramuscular with adjuvant (p>0.05 vs. alum or MPL adjuvants), and the level of protection was similar regardless of adjuvant employed, to that provided by heat-killed whole organism vaccine group (p>0.05 for all).

FIG. 3 shows the results of the experiments evaluating oral bone loss in vivo. (A) BALB/c mice were randomized into groups (G1-6) and immunized animals received 3 intramuscular injections of combined protein cocktail in respective adjuvant, or in injection-grade saline at 2-week intervals (primary and 2 boosts; red arrows). Immunization control group (G3) received heat-killed P. gingivalis (equivalent to 1×10⁷ CFU/injection). All animals were placed on 10-day sulphamethoxazole/trimethoprim (antibiotics) in drinking water, followed by removal of antibiotics three days prior to mock oral challenge (G1), or P. gingivalis oral challenge (3× over a 1-week period; G2-6). After completion of oral challenge (0 wks.), animals were allowed rest for six weeks and then sacrificed. FIG. 3 provides the results, showing the average distance between cementum enamel junction (CEJ) and alveolar bone crest (ABC) in mm±SEM, #=p<0.001 vs. G1 (unchallenged), ***=p<0.01 vs. G2 (P. gingivalis oral challenge only) (using ANOVA with Dunns multiple comparisons). 

The invention claimed is:
 1. An immunogenic composition comprising at least one recombinant polypeptide wherein the at least one polypeptide comprises: (a) an Mfa1 antigen sequence, wherein the Mfa1 antigen sequence comprises a sequence having at least 90% sequence homology to SEQ ID NO: 4; and (b) an HA1 antigen sequence, an HA2 antigen sequence, or both an HA1 antigen sequence and an HA2 antigen sequence, wherein (i) the HA1 antigen sequence comprises a sequence having at least 80% sequence homology to SEQ ID NO: 5, and (ii) the HA2 antigen sequence comprises a sequence having at least 80% sequence homology to SEQ ID NO:
 6. 2. The immunogenic composition according to claim 1 wherein the at least one recombinant polypeptide comprises a first recombinant polypeptide comprising: (a) the Mfa1 antigen sequence and the HA1 antigen sequence; (b) the Mfa1 antigen sequence and the HA2 antigen sequence; or (c) the Mfa1 antigen sequence, the HA1 antigen sequence, and the HA2 antigen sequence.
 3. The immunogenic composition according to claim 1 wherein the at least one recombinant polypeptide comprises: (a) a first recombinant polypeptide comprising the Mfa1 antigen sequence; and (b) a second recombinant polypeptide comprising the HA1 antigen sequence, the HA2 antigen sequence, or both the HA1 antigen sequence and the HA2 antigen sequence.
 4. The immunogenic composition according to claim 1 wherein the at least one recombinant polypeptide comprises: (a) a first recombinant polypeptide comprising the Mfa1 antigen sequence; (b) a second recombinant polypeptide comprising the HA1 antigen sequence; and (c) a third recombinant polypeptide comprising the HA2 antigen sequence.
 5. The immunogenic composition of claim 1, wherein the Mfa1 antigen sequence comprises a sequence having at least 90% sequence homology to SEQ ID NO:4, the HA1 antigen sequence comprises a sequence having at least 80% sequence homology to SEQ ID NO:5, and the HA2 antigen sequence comprises a sequence having at least 90% sequence homology to SEQ ID NO:6.
 6. The immunogenic composition of claim 1, wherein the Mfa1 antigen sequence comprises a sequence having at least 90% sequence homology to SEQ ID NO:4, the HA1 antigen sequence comprises a sequence having at least 90% sequence homology to SEQ ID NO:5, and the HA2 antigen sequence comprises a sequence having at least 80% sequence homology to SEQ ID NO:6.
 7. A vaccine formulation, comprising the immunogenic composition of claim 1 and at least one excipient.
 8. The vaccine formulation of claim 7, wherein the at least one excipient is selected from vehicles, solubilizers, emulsifiers, stabilizers, preservatives, isotonicity agents, buffer systems, dispersants, diluents, viscosity modifiers, and absorption enhancers.
 9. The vaccine formulation of claim 8, further including an adjuvant.
 10. A method for immunizing a subject against periodontal disease, comprising administering to the subject an immunologically effective amount of the immunogenic composition of claim
 1. 11. A method for immunizing a subject against periodontal disease, comprising administering to the subject an immunologically effective amount of the vaccine formulation of claim
 7. 12. The method of claim 11, wherein the periodontal disease is associated with a Porphyromonas bacterium selected from P. gingivalis, P. gulae, P. cangingivalis, P. gingivicanis, P. canoris, P. salivosa, and P. circumdentaria.
 13. The method of claim 12, wherein the Porphyromonas bacterium is P. gulae.
 14. The method of claim 13, wherein the subject is a non-human mammal.
 15. The method of claim 11, wherein the vaccine formulation comprises a sterile injectable solution and is administered to the subject by injection.
 16. The method of claim 11, wherein the subject exhibits symptoms of periodontitis and the vaccine formulation is administered as a therapeutic vaccine.
 17. A method for reducing the risk of periodontitis developing in a subject, the method comprising administering to the subject an immunologically effective amount of the immunogenic composition of claim
 1. 18. A method for reducing the risk of periodontitis developing in a subject, the method comprising administering to the subject an immunologically effective amount of the vaccine formulation of claim
 7. 19. The method of claim 18, wherein the subject has at least one risk factor of developing periodontitis.
 20. The method of claim 19, wherein the at least one risk factor is selected from age, genetic predisposition, a systemic disease, the presence of endodontic lesions or abscesses, or a combination thereof.
 21. A method for reducing bone loss caused by periodontal disease, comprising administering to a subject in need of such treatment an immunologically effective amount of the composition of claim
 1. 22. A method for preventing bone loss caused by periodontal disease, comprising administering to a subject in need of such treatment an immunologically effective amount of the vaccine formulation of claim
 7. 23. A method for reducing inflammation caused by periodontal disease, comprising administering to a subject in need of such treatment an effective amount of the immunogenic composition of claim
 1. 24. A method for reducing inflammation caused by periodontal disease, comprising administering to a subject in need of such treatment an effective amount of the vaccine formulation of claim
 7. 25. A vaccine formulation, comprising the immunogenic composition of claim 4 and at least one excipient.
 26. A method for immunizing a subject against periodontal disease, comprising administering to the subject an immunologically effective amount of the immunogenic composition of claim
 4. 27. A method for immunizing a subject against periodontal disease, comprising administering to the subject an immunologically effective amount of the vaccine formulation of claim
 25. 28. The method of claim 12, wherein the Porphyromonas bacterium is P. cangingivalis or P. gingivicanis.
 29. The method of claim 28, wherein the subject is a non-human mammal. 